The present invention relates to thermoplastic elastomer composition laminates particularly useful for tire and other industrial rubber applications and processes for producing such compositions.
Compositions exhibiting low gas permeability performance (i.e., functioning as a gas barrier) composed of thermoplastic resin/thermoplastic resin-based blends such as a high density polyethylene resin and nylon 6 or nylon 66 (HDPE/PA6.66), a polyethylene terephthalate and aromatic nylon (PET/MXD6), a polyethylene terephthalate and vinyl alcohol-ethylene copolymer (PET/EVOH), where one thermoplastic resin is layered over the other layer to form plural layers by molding, and processes for producing the same. However, since these materials are thermoplastic resin/thermoplastic resin blends, while they are superior in gas barrier performance, they lack flexibility, and therefore, such films are subject to failure if they are used in a vehicle tire which is subject to significant stress and flexing.
Further, there are also examples of the use of a thermoplastic elastomer composed of a rubber and a thermoplastic resin for use as an innerliner or in a tire; but in general, a flexible material of the type disclosed therein and having superior durability has low heat resistance. With a thermoplastic elastomer using a thermoplastic resin having a melting point less than the tire vulcanization temperature as a matrix, when the tire vulcanization bladder is released at the end of the tire vulcanization cycle, the tire inside surface is subject to appearance defects due to the thermoplastic resin sticking to or rubbing against the vulcanization bladder.
When preparing tire innerliners for assembly with a tire carcass, a thermoplastic elastomer may be co-extruded together with an adhesive layer in two layers in cylindrical shapes. If the adhesive layer arranged at the outside is too tacky, it will stick to the take-up roll at the time of shaping and seriously degrade the workability. Further, this requires the insertion of release paper, Mylar® film, etc., between the tubular materials at the time of take-up-which is a problem in terms of cost and transport weight. On the other hand, if the adhesive layer is insufficiently tacky, at the time of tire production, there is the problem that the thermoplastic elastomer layer may end up peeling off from the tire carcass thereby making tire manufacturing difficult. These limitations of the prior art approaches to achieving an adhesive coated thermoplastic elastomeric layer for tire linnerliners suggest that there is a continuing need for improvements, as have been accomplished by use of the processes and compositions of the present invention.